Re: Intel Dev says "Stop using OnDemand!!!"

Re: Intel Dev says "Stop using OnDemand!!!"

I suppose the "new" part is related to the kernel option "CONFIG_X86_INTEL_PSTATE" .

Arjan van de Ven wrote:

The new code in the 3.9 kernel, under, CONFIG_X86_INTEL_PSTATE, is a fresh approach to all of this.First of all, we use the enumeration of the hardware capabilities that Intel processors provide, which means we're not limited by what ACPI can express (ACPI is a bit too limiting on anything modern).We also, and I realize this might be controversial, combine the control algorithm with the cpu driver in one. The reality is that such control algorithms are CPU specific, the notion of a generic "for all cpus" governors is just outright flawed; hardware behavior is key to the algorithm in the first place....

The algorithm also, and we'll be tuning this for a while still, much more in line with modern hardware behavior.... we are seeing very significant power/performance improvements with the 3.9/3.10rc code over using ondemand, and a much smaller performance gap with the "performance" governor in terms of performance.

the 3.9/3.10-rc1 code right now only supports SNB cpus, but the CPU ID of IVB is about to added as well.

Re: Intel Dev says "Stop using OnDemand!!!"

Just installed thermald-git from aur which should implement Intels "new" methods of powersaving for my snb-cpu. So far its just an impression but power usage (as measured by powertop) is 2 W less then before during idle.

Re: Intel Dev says "Stop using OnDemand!!!"

There is some potential for confusion from the pstate governors' naming: the "powersave" governor seems to be the "new" cpufreq_ondemand, at least it does not behave like cpufreq_powersave (which runs the cpu at the minimum frequency).

@tobsen:if you run the stock arch kernel on snb and haven't changed any settings regarding the governor, you get "powersave" by default.

Re: Intel Dev says "Stop using OnDemand!!!"

falconindy wrote:

This isn't anything new -- Intel has been talking about the "race to idle" for years.

This isn't about Race To Idle. This is about scrapping cpufreq / cpupowered at the kernel level and replacing it with proper CPU drivers. It really doesn't make much sense to have a governor (*looks at OnDemand*) that is supposed to be all about staying idle, have to continually wake up the CPU FROM idle to do its job.

It doesn't matter how much training you have. A broken rib is still a broken rib.

Re: Intel Dev says "Stop using OnDemand!!!"

To anyone who's installed the Thermald package from the AUR, I (geric) added a small comment to the package. The package A) Needs a maintainer (currently orphaned) B) It also requires the package "msr-tools" from the AUR and requires that the module "msr" be auto-loaded on boot to fully function. Just an FYI

It doesn't matter how much training you have. A broken rib is still a broken rib.

Re: Intel Dev says "Stop using OnDemand!!!"

tobsen wrote:

Just installed thermald-git from aur which should implement Intels "new" methods of powersaving for my snb-cpu. So far its just an impression but power usage (as measured by powertop) is 2 W less then before during idle.

Re: Intel Dev says "Stop using OnDemand!!!"

graysky wrote:

tobsen wrote:

Just installed thermald-git from aur which should implement Intels "new" methods of powersaving for my snb-cpu. So far its just an impression but power usage (as measured by powertop) is 2 W less then before during idle.

Just FYI - thermald is not required for the pstates driver.

True, it just helps. More of a complete power management suite. I know thanks to thermald and the new pstate driver my system is about 10degrees cooler than usual and stays that way even under load.

It doesn't matter how much training you have. A broken rib is still a broken rib.

Re: Intel Dev says "Stop using OnDemand!!!"

Thanks for posting the heads up in the #1 link from me as well. I had trouble with an SNB i3 in the current kernel with "powersave" enabled via tlp (cpupower defaults commented out). The frequency would stick to the lower bounds min_freq. and I was looking into it when I read this.

Turns out not using the tlp options for frequency scaling and setting "performance" in cpupower brings the machine back to normal. Moreover the powerconsumption (believing powertop for now) appears to be back to low levels from 3.7.9. despite the new governor (~10%+ less than with any 3.8 kernel on this machine). Good start, going to be interesting how this develops.

Re: Intel Dev says "Stop using OnDemand!!!"

Looks like intel_pstate isn't able to change CPU's frequency (always max, also on powersave) when it's used in combination with CONFIG_NO_HZ_FULL (full tickless) on 3.10 rc2 (patched for ivy).Can someone confirm?

Re: Intel Dev says "Stop using OnDemand!!!"

kelloco2 wrote:

Ivy Bridge will be supported in the kernel 3.10?

This is covered in the Google+ link above. But I'll tell you what it said. Apparently, the merge window closed before it was felt that IVB had gotten enough testing to add its code into the sources. But since it is a simple one line addition that does nothing more than actually add the IVB code to the list of supported chips, there was hope that it would be allowed to merge after the window was closed. Soooo maybe.